Genetic and molecular mechanism for distinct clinical phenotypes conveyed by allelic truncating mutations implicated in FBN1

BACKGROUND

The molecular and genetic mechanisms by which different single nucleotide variant alleles in specific genes, or at the same genetic locus, cause distinct disease phenotypes often remain unclear. Allelic truncating mutations of FBN1 could cause either classical Marfan syndrome (MFS) or a more complicated phenotype associated with Marfanoid-progeroid-lipodystrophy syndrome (MPLS).

METHODS

We investigated a small cohort, encompassing two classical MFS and one MPLS subjects from China, whose clinical presentation included scoliosis potentially requiring surgical intervention. Targeted next generation sequencing was performed on all the participants. We analyzed the molecular diagnosis, clinical features, and the potential molecular mechanism involved in the MPLS subject in our cohort.

RESULTS

We report a novel de novo FBN1 mutation for the first Chinese subject with MPLS, a more complicated fibrillinopathy, and two subjects with more classical MFS. We further predict that the MPLS truncating mutation, and others previously reported, is prone to escape the nonsense-mediated decay (NMD), while MFS mutations are predicted to be subjected to NMD. Also, the MPLS mutation occurs within the glucogenic hormone asprosin domain of FBN1. In vitro experiments showed that the single MPLS mutation p.Glu2759Cysfs*9 appears to perturb proper FBN1 protein aggregation as compared with the classical MFS mutation p.Tyr2596Thrfs*86. Both mutations appear to upregulate SMAD2 phosphorylation in vitro.

CONCLUSION

We provide direct evidence that a dominant-negative interaction of FBN1 potentially explains the complex MPLS phenotypes through genetic and functional analysis. Our study expands the mutation spectrum of FBN1 and highlights the potential molecular mechanism for MPLS.

Familial Aortopathies - State of the Art Review

Aortopathies are conditions that result in aortic dilatation, aneurysm formation and dissection. Familial aortopathies (perhaps better known as heritable thoracic aortic aneurysm and dissection, h-TAAD, as not all have a positive family history) are recognised to have an underlying genetic cause and affect the aorta, predisposing it to the above pathologies. These conditions can also affect the extra-aortic vasculature, particularly large elastic arteries and other body systems. Mutations in a number of genes have been associated with h-TAAD. However, not all affected families have a pathogenic gene variant identified-highlighting the importance of a three-generational family history and the likely role of both environmental factors and future gene discoveries in furthering knowledge. Survival has improved over the last few decades, essentially due to surgical intervention. The benefit of identifying affected individuals depends upon a regular surveillance program and timely referral for surgery before complications such as dissection. Further research is required to appreciate fully the effects of individual gene variants and improve evidence for prophylactic medical therapy, as well as to understand the effect of h-TAAD on quality of life and life choices, particularly around exercise and pregnancy, for affected individuals. This will be complemented by laboratory-based research that seeks to understand the tissue pathways that underlie development of arterial pathology, ideally providing targets for novel medical therapies and a means of non-invasively identifying individuals at increased vascular risk to reduce dissection, which remains a devastating life-threatening event.

Genetics' Piece of the PI: Inferring the Origin of Complex Traits and Diseases from Proteome-Wide Protein-Protein Interaction Dynamics

How do common and rare genetic polymorphisms contribute to quantitative traits or disease risk and progression? Multiple human traits have been extensively characterized at the genomic level, revealing their complex genetic architecture. However, it is difficult to resolve the mechanisms by which specific variants contribute to a phenotype. Recently, analyses of variant effects on molecular traits have uncovered intermediate mechanisms that link sequence variation to phenotypic changes. Yet, these methods only capture a fraction of genetic contributions to phenotype. Here, in reviewing the field, it is proposed that complex traits can be understood by characterizing the dynamics of biochemical networks within living cells, and that the effects of genetic variation can be captured on these networks by using protein-protein interaction (PPI) methodologies. This synergy between PPI methodologies and the genetics of complex traits opens new avenues to investigate the molecular etiology of human diseases and to facilitate their prevention or treatment.

NGS analysis in Marfan syndrome spectrum: Combination of rare and common genetic variants to improve genotype-phenotype correlation analysis

The diagnosis of Marfan spectrum includes a large number of clinical criteria. Although the identification of pathogenic variants contributes to the diagnostic process, its value to the prediction of clinical outcomes is still limited. An important novelty of the present study is represented by the statistical approach adopted to investigate genotype-phenotype correlation. The analysis has been improved considering the extended genetic information obtained by Next Generation Sequencing (NGS) and combining the effects of both rare and common genetic variants in an inclusive model. To this aim a cohort of 181 patients were analyzed with a NGS panel including 11 genes associated with Marfan spectrum. The genotype-phenotype correlation was also investigated considering the possibility to predict presence of a pathological mutation in Marfan syndrome (MFS) main genes based only on the analysis of phenotypic traits. Results obtained indicate that information about clinical traits can be summarized in a new variable that resulted significantly associated with the probability to find a pathological mutation in MFS main genes. This is important since the choice of the genetic test is often influenced by the phenotypic characterization of patients. Moreover, both rare and common variants were found to significantly contribute to clinical spectrum and their combination allowed to increase the percentage of phenotype variability that could be explained based on genetic factors. Results highlight the opportunity to take advantage of the overall genetic information obtained by NGS data to have a better clinical classification of patients.

Transforming Growth Factor-β Signaling in Immunity and Cancer

Transforming growth factor (TGF)-β is a crucial enforcer of immune homeostasis and tolerance, inhibiting the expansion and function of many components of the immune system. Perturbations in TGF-β signaling underlie inflammatory diseases and promote tumor emergence. TGF-β is also central to immune suppression within the tumor microenvironment, and recent studies have revealed roles in tumor immune evasion and poor responses to cancer immunotherapy. Here, we present an overview of the complex biology of the TGF-β family and its context-dependent nature. Then, focusing on cancer, we discuss the roles of TGF-β signaling in distinct immune cell types and how this knowledge is being leveraged to unleash the immune system against the tumor.

Sleep apnea and the impact on cardiovascular risk in patients with Marfan syndrome

Background

Marfan syndrome (MFS) is an inherited connective tissue disorder characterized by ectopia lentis, aortic root dilation and dissection and specific skeletal features. Obstructive sleep apnea (OSA) in MFS has been described earlier but the prevalence and its relation with the cardiovascular risk is still controversial. This study aimed to further investigate these aspects.

Methods

In this prospective longitudinal study, we performed an attended polysomnography in 40 MFS patients (60% women, 37 ± 12.8 years) and evaluated several cardiovascular parameters through echocardiography, resting electrocardiogram, 24 hr‐Holter monitoring and serum NT‐ProBNP measurements.

Results

We found that OSA was present in 42.5% of the patients and that higher body mass index was the most important factor associated with the presence of OSA. We observed that overweight was present in 27.5% of the patients in the whole cohort and in 55.6% if >40 years. Furthermore, when evaluating the impact of OSA on the cardiovascular system, we observed that patients with OSA tended to have higher systolic blood pressure, larger distal aortic diameters and a higher prevalence of ventricular arrhythmia. These differences were, however, not significant after adjusting for confounders.

Conclusions

Our study shows a high prevalence of OSA and a high prevalence of overweight in MFS patients. We found some trends between OSA and cardiovascular features but we could not establish a solid association. Our study, however might be underpowered, and a multicenter collaborative study could be very useful to answer some important open questions.

VCAN Canonical Splice Site Mutation is Associated With Vitreoretinal Degeneration and Disrupts an MMP Proteolytic Site

Purpose

To gain insight into the pathophysiology of vitreoretinal degeneration, the clinical course of three family members with Versican Vitreoretinopathy (VVR) is described, and a canonical splice site mutation in the gene encoding for versican (VCAN) protein was biochemically analyzed.

Methods

A retrospective chart review, human eye histopathology, Sanger DNA sequencing, protein structural modeling, and in vitro proteolysis assays were performed.

Results

The proband (II:1), mother (I:2), and younger sibling (II:2) suffered retinal degeneration with foveal sparing and retinal detachments with proliferative vitreoretinopathy, features that were confirmed on histopathologic analysis. All affected members carried a heterozygous adenine to guanine variant (c.4004-2A>G) predicted to result in exon 8 skipping or the deletion of 13 amino acids at the beginning of the GAGβ chain (VCAN p.1335-1347). This deleted region corresponded to a putative MMP cleavage site, validated using fluorescence resonance energy transfer (FRET)-based proteolysis assays. Proteomic network analysis identified 10 interacting partners in the human vitreous and retina linked to retinal detachment and degeneration.

Conclusions

VVR causes significant ocular disease, including retinal detachment and retinal dystrophy. The intronic VCAN mutation removes an MMP cleavage site, which alters versican structure and results in abnormal vitreous modeling. Disruption of a versican protein network may underlie clinicopathologic disease features and point to targeted therapies.

CRISPR/Cas9 Delivery Mediated with Hydroxyl-Rich Nanosystems for Gene Editing in Aorta

A CRISPR/Cas9 system has emerged as a powerful tool for gene editing to treat genetic mutation related diseases. Due to the complete endothelial barrier, effective delivery of the CRISPR/Cas9 system to vasculatures remains a challenge for in vivo gene editing of genetic vascular diseases especially in aorta. Herein, it is reported that CHO-PGEA (cholesterol (CHO)-terminated ethanolamine-aminated poly(glycidyl methacrylate)) with rich hydroxyl groups can deliver a plasmid based pCas9-sgFbn1 system for the knockout of exon 10 in Fbn1 gene. This is the first report of a polycation-mediated CRISPR/Cas9 system for gene editing in aorta of adult mice. CHO-PGEA/pCas9-sgFbn1 nanosystems can effectively contribute to the knockout of exon 10 in Fbn1 in vascular smooth muscle cells in vitro, which leads to the change of the phosphorylation of Smad2/3 and the increased expression of two downstream signals of Fbn1: Mmp-2 and Ctgf. For in vivo application, the aortic enrichment of CHO-PGEA/Cas9-sgFbn1 is achieved by administering a pressor dose of angiotensin II (Ang II). The effects of the pCas9-sgFbn1 system targeting Fbn1 demonstrate an increase in the expression of Mmp-2 and Ctgf in aorta. Thus, the combination of CHO-PGEA/pCas9-sgFbn1 nanosystems with Ang II infusion can provide the possibility for in vivo gene editing in aorta.

Elastic fibers and elastin receptor complex: Neuraminidase-1 takes the center stage

Extracellular matrix (ECM) has for a long time being considered as a simple architectural support for cells. It is now clear that ECM presents a fundamental influence on cells driving their phenotype and fate. This complex network is highly specialized and the different classes of macromolecules that comprise the ECM determine its biological functions. For instance, collagens are responsible for the tensile strength of tissues, proteoglycans and glycosaminoglycans are essential for hydration and resistance to compression, and glycoproteins such as laminins facilitate cell attachment. The largest structures of the ECM are the elastic fibers found in abundance in tissues suffering high mechanical constraints such as skin, lungs or arteries. These structures present a very complex composition whose core is composed of elastin surrounded by a microfibrils mantle. Elastogenesis is a tightly regulated process involving the sialidase activity of the Neuraminidase-1 (Neu-1) sub-unit of the Elastin Receptor Complex. Interestingly, Neu-1 subunit also serves as a sensor of elastin degradation via its ability to transmit elastin-derived peptides signaling. Finally, reports showing that neuraminidase activity is able to regulate TGF-β activation raises questions about a possible role for Neu-1 in elastic fibers remodeling. In this mini review, we develop the concept of the regulation of the whole life of elastic fibers through an original scope, the key role of Neu-1 sialidase enzymatic activity.

Characterization of Two Novel Intronic Variants Affecting Splicing in FBN1-Related Disorders

FBN1 encodes fibrillin 1, a key structural component of the extracellular matrix, and its variants are associated with a wide range of hereditary connective tissues disorders, such as Marfan syndrome (MFS) and mitral valve–aorta–skeleton–skin (MASS) syndrome. Interpretations of the genomic data and possible genotype–phenotype correlations in FBN1 are complicated by the high rate of intronic variants of unknown significance. Here, we report two unrelated individuals with the FBN1 deep intronic variants c.6872-24T>A and c.7571-12T>A, clinically associated with MFS and MASS syndrome, respectively. The individual carrying the c.6872-24T>A variant is positive for aortic disease. Both individuals lacked ectopia lentis. In silico analysis and subsequent mRNA study by RT-PCR demonstrated the effect of the identified variant on the splicing process in both cases. The c.6872-24T>A and c.7571-12T>A variants generate the retention of intronic nucleotides and lead to the introduction of a premature stop codon. This study enlarges the mutation spectrum of FBN1 and points out the importance of intronic sequence analysis and the need for integrative functional studies in FBN1 diagnostics.

Application of next-generation sequencing to screen for pathogenic mutations in 123 unrelated Chinese patients with Marfan syndrome or a related disease

Marfan syndrome (MFS) is a systemic connective tissue disease principally affecting the ocular, skeletal and cardiovascular systems. This autosomal dominant disorder carries a prevalence of 1:3,000 to 1:5,000. This study aims to define the mutational spectrum of MFS related genes in Chinese patients and to establish genotype-phenotype correlations in MFS. Panel-based targeted next-generation sequencing was used to analyze the FBN1, TGFBR1 and TGFBR2 genes in 123 unrelated Chinese individuals with MFS or a related disease. Genotype-phenotype correlation analyses were performed in mutation-positive patients. The results showed that 97 cases/families (78.9%; 97/123) harbor at least one (likely) pathogenic mutation, most of which were in FBN1; four patients had TGFBR1/2 mutations; and one patient harbored a SMAD3 mutation. Three patients had two FBN1 mutations, and all patients showed classical MFS phenotypes. Patients with a dominant negative-FBN1 mutation had a higher prevalence of ectopia lentis (EL). Patients carrying a haploinsufficiency-FBN1 mutation tended to have aortic dissection without EL. This study extends the spectrum of genetic backgrounds of MFS and enriches our knowledge of genotype-phenotype correlations.

Biomaterials to Mimic and Heal Connective Tissues

Connective tissue is one of the four major types of animal tissue and plays essential roles throughout the human body. Genetic factors, aging, and trauma all contribute to connective tissue dysfunction and motivate the need for strategies to promote healing and regeneration. The goal here is to link a fundamental understanding of connective tissues and their multiscale properties to better inform the design and translation of novel biomaterials to promote their regeneration. Major clinical problems in adipose tissue, cartilage, dermis, and tendon are discussed that inspire the need to replace native connective tissue with biomaterials. Then, multiscale structure-function relationships in native soft connective tissues that may be used to guide material design are detailed. Several biomaterials strategies to improve healing of these tissues that incorporate biologics and are biologic-free are reviewed. Finally, important guidance documents and standards (ASTM, FDA, and EMA) that are important to consider for translating new biomaterials into clinical practice are highligted.

The effect of physiological stretch and the valvular endothelium on mitral valve proteomes

IMPACT STATEMENT

This work is important to the field of heart valve pathophysiology as it provides new insights into molecular markers of mechanically induced valvular degeneration as well as the protective role of the valvular endothelium. These discoveries reported here advance our current knowledge of the valvular endothelium and how its removal essentially takes valve leaflets into an environmental shock. In addition, it shows that static conditions represent a mild pathological state for valve leaflets, while 10% cyclic stretch provides valvular cell quiescence. These findings impact the field by informing disease stages and by providing potential new drug targets to reverse or slow down valvular change before it affects cardiac function.

Pseudoacromegaly

Individuals with acromegaloid physical appearance or tall stature may be referred to endocrinologists to exclude growth hormone (GH) excess. While some of these subjects could be healthy individuals with normal variants of growth or physical traits, others will have acromegaly or pituitary gigantism, which are, in general, straightforward diagnoses upon assessment of the GH/IGF-1 axis. However, some patients with physical features resembling acromegaly - usually affecting the face and extremities -, or gigantism - accelerated growth/tall stature - will have no abnormalities in the GH axis. This scenario is termed pseudoacromegaly, and its correct diagnosis can be challenging due to the rarity and variability of these conditions, as well as due to significant overlap in their characteristics. In this review we aim to provide a comprehensive overview of pseudoacromegaly conditions, highlighting their similarities and differences with acromegaly and pituitary gigantism, to aid physicians with the diagnosis of patients with pseudoacromegaly.

Tall Stature: A Challenge for Clinicians

Clinicians generally use the term "tall stature" to define a height more than two standard deviations above the mean for age and sex. In most cases, these subjects present with familial tall stature or a constitutional advance of growth which is diagnosed by excluding the other conditions associated with overgrowth. Nevertheless, it is necessary to be able to identify situations in which tall stature or an accelerated growth rate indicate an underlying disorder. A careful physical evaluation allows the classification of tall patients into two groups: those with a normal appearance and those with an abnormal appearance including disproportion or dysmorphism. In the first case, the growth rate has to be evaluated and, if it is normal for age and sex, the subjects may be considered as having familial tall stature or constitutional advance of growth or they may be obese, while if the growth rate is increased, pubertal status and thyroid function should be evaluated. In turn, tall subjects having an abnormal appearance can be divided into proportionate and disproportionate syndromic patients. Before initiating further investigations, the clinician needs to perform both a careful physical examination and growth evaluation. To exclude pathological conditions, the cause of tall stature needs to be considered, although most children are healthy and generally do not require treatment to inhibit growth progression. In particular cases, familial tall stature subject can be treated by inducing puberty early and leading to a complete fusion of the epiphyses, so final height is reached. This review aims to provide proposals about the management of tall children.

Early posterior vitreous detachment is associated with LAMA5 dominant mutation

BACKGROUND

Extracellular matrix molecular components, previously linked to multisystem syndromes include collagens, fibrillins and laminins. Recently, we described a novel multisystem syndrome caused by the c.9418G>A p.(V3140M) mutation in the laminin alpha-5 (LAMA5) gene, which affects connective tissues of all organs and apparatus in a three generation family. In the same family, we have also reported a myopic trait, which, however, was linked to the Prolyl 4-hydroxylase subunit alpha-2 (P4HA2) gene. Results of investigation on vitreous changes and their pathogenesis are reported in the present study.

MATERIALS AND METHODS

Nineteen family individuals underwent complete ophthalmic examination including best-corrected visual acuity (BCVA), fundus examination, fundus photography, intraocular pressure measurement, axial length measurement using ocular biometry, Goldmann visual field examination, standard electroretinogram, SD-OCT. Segregation analysis of LAMA5 and P4HA2 mutations was performed in enrolled members.

RESULTS

The vitreous alterations fully segregated with LAMA5 mutation in both young and adult family members. Slight reduction of retinal thickness and peripheral retinal degeneration in only two patients were reported.

CONCLUSIONS

In this work we showed that PVD is a common trait of LAMA5 multisystem syndrome, therefore occurring as an age-unrelated trait. We hypothesize that the p.(V3140M) mutation results in a reduction of retinal inner limiting membrane (ILM) stability, leading to a derangement in the macromolecular structure of the vitreous gel, and PVD. Further investigations will be necessary to elucidate the role of wild type and mutated LAMA5 in the pathogenesis of PVD.

Aortic treatment in connective tissue disease

Connective tissue disease (CTD) represents a group of genetic conditions characterized by disruptive matrix remodeling. When this process involves aortic and vascular wall, patients with CTD have a high risk of developing arterial aneurysms, dissections and ruptures. Open surgical repair is still the gold standard therapy for patients with CTD with reasonable morbidity and mortality risk. The surgical treatment of CTD often requires multiple operations. In the endovascular era, fenestrated and branched stent grafts may play a role in reducing the complications of multiple open operations. Although the long-term results of endovascular treatment in the setting of CTD are unknown, it is generally accepted that endovascular treatment is restricted to selected patients with high surgical risk. In an emergency setting, endovascular intervention can serve as a lifesaving bridge to elective open aortic repair. Aortic centers performing a large volume of complex open and endovascular aortic repairs have started to combine these two techniques in a staged fashion. The goal is to reduce the morbidity and mortality associated with extensive aortic repairs in CTD patients. For this reason, recommend endovascular therapy when a "graft-to-graft" approach is possible. In this scenario, the surgeon who performs the open repair must take into consideration future interventions. Surgical repair in any aortic segment should allow creation of proximal and distal landing zones over 4 cm to secure the sealing of a future stent graft. Connective tissue disease should be treated with a multidisciplinary approach, in high volume centers. Endovascular treatment represents a potential option in patients at high risk for open repair. Staged hybrid procedures have emerged as a way to reduce spinal cord ischemia and avoid multiple open surgeries. The aim of this article is to discuss the management of aortic diseases in CTD, focusing on to the role of standard open surgery and emerging endovascular treatment, and to give an overview of the few series published regarding this topic with a small number of patients.

TGF-β signaling promotes tumor vasculature by enhancing the pericyte-endothelium association

Background

The breast cancer microenvironment promotes tumor vascularization through the complex interactions involving tumor-associated fibroblasts (TAFs). Emerging data indicate that TAFs increase production and signaling by TGF-β cytokines, while the role of TGF-β signaling in the regulation of tumor blood vessels is not fully understood. The current study presents evidence that TAFs enhance the organization of tumor blood capillaries, and TGF-β signaling plays an important role in this response.

Methods

Tumor vascularization was studied in xenograft models of breast carcinoma cells, alone and in combination with fibroblasts. TGF-β signaling in breast cancer cells was modulated by expression of kinase-inactive TGFBR1-K232R (dnTGFBR1) or constitutive-active TGFBR1-T204D (caTGFBR1) receptor mutants. The architecture of tumor blood capillaries was assessed by immune-histochemical analysis of endothelium and pericytes. The role of TGF-β-Smad signaling in fibronectin expression was examined using adenoviral transduction of signaling components.

Results

Our studies revealed that TAFs significantly increase the lumen size of blood microvessels. Inactivation of TGF-β signaling in tumor cells by dnTGFBR1 reduced the microvessel density and lumen sizes, decreasing tumor growth. In contrast, caTGFBR1-tumors exhibited greater vessel density and lumen sizes. Tumors with inactive dnTGFBR1 showed lower amounts of TAFs, while caTGFBR1 increased amounts of TAFs compared to the control. Inspection of pericytes and endothelial cells in tumor vasculature revealed that TAFs enhanced vessel coverage by pericytes, vascular cells supporting capillaries. This effect was impaired in dnTGFBR1-tumors, whereas active caTGFBR1 enhanced the association of pericytes with endothelium. Accordingly, dnTGFBR1-tumors exhibited the presence of hemorrhages, a sign of fragile blood vessels. Biochemical analysis showed that TGFBR1-SMAD signaling up-regulates fibronectin, a prominent regulator of endothelium-pericyte interactions.

Conclusions

The current study indicates that tumor-fibroblast crosstalk enhances tumor vascularization by increasing the pericyte-endothelium association via a mechanism involving the TGFβ-fibronectin axis. The tumor-fibroblast model represents a useful system for dissecting the complex interactions governing tumor angiogenesis and developing new approaches to therapeutic targeting tumor vasculature.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4587-z) contains supplementary material, which is available to authorized users.

Anabolic Therapy for the Treatment of Osteoporosis in Childhood

PURPOSE OF REVIEW

Numerous forms of osteoporosis in childhood are characterized by low bone turnover (for example, osteoporosis due to neuromuscular disorders and glucocorticoid exposure). Anti-resorptive therapy, traditionally used to treat osteoporosis in the young, is associated with further reductions in bone turnover, raising concerns about the long-term safety and efficacy of such therapy. These observations have led to increasing interest in the role of anabolic therapy to treat pediatric osteoporosis.

RECENT FINDINGS

While growth hormone and androgens appears to be relatively weak anabolic modulators of bone mass, emerging therapies targeting bone formation pathways (anti-transforming growth factor beta antibody and anti-sclerostin antibody) hold considerable promise. Teriparatide remains an attractive option that merits formal study for patients post-epiphyseal fusion, although it must be considered that adult studies have shown its effect is blunted when administered following bisphosphonate therapy. Mechanical stimulation of bone through whole body vibration therapy appears to be much less effective than bisphosphonate therapy for treating osteoporosis in children. New anabolic therapies which target important pathways in skeletal metabolism merit further study in children, including their effects on fracture risk reduction and after treatment discontinuation.

Identification of Novel Causal FBN1 Mutations in Pedigrees of Marfan Syndrome

Marfan syndrome (MFS) is an autosomal dominant genetic disorder of the connective tissue, typically characteristic of cardiovascular manifestations, valve prolapse, left ventricle enlargement, and cardiac failure. Fibrillin-1 (FBN1) is the causative gene in the pathogenesis of MFS. Patients with different FBN1 mutations often present more considerable phenotypic variation. In the present study, three affected MFS pedigrees were collected for genetic analysis. Using next-generation sequencing (NGS) technologies, 3 novel frameshift pathogenic mutations which are cosegregated with affected subjects in 3 pedigrees were identified. These novel mutations provide important diagnostic and therapeutic insights for precision medicine in MFS, especially regarding the lethal cardiovascular events.

Redo Aortic Root Operations in Patients with Marfan Syndrome

Aortic root aneurysm is the most common cardiovascular manifestation requiring surgical intervention in patients with Marfan syndrome (MFS), a heritable thoracic aortic disease. Elective replacement of the aortic root is the treatment of choice for patients with aneurysmal complications of the aortic root and ascending aorta. There are two basic approaches to aortic root replacement: valve-sparing (VS) and valve-replacing (VR) techniques. After successful aortic root replacement surgery, several patients with MFS may develop a late complication related to their aortic disease process, such as developing a pseudoaneurysm of the coronary artery reattachment buttons, aneurysmal expansion, or aortic dissection in the remaining native aorta. These patients may also develop other late complications that are not specifically related to the heritable thoracic aortic disease, such as infections that can lead to dehiscence of some or all of the distal or proximal anastomosis. Because these complications are rare, the clinical volume of reoperations of the aortic root in patients with MFS is low, making it difficult to assess contemporary experiences with these procedures. Only a few published reports have examined reoperative aortic root surgery in patients with MFS, each of which had only a small series of patients. Herein, we describe our contemporary experience with reoperative aortic root replacement in patients with MFS and provide our operative approach for these uncommon procedures.

Bio-chemo-mechanics of thoracic aortic aneurysms

Most thoracic aortic aneurysms (TAAs) occur in the ascending aorta. This review focuses on the unique bio-chemo-mechanical environment that makes the ascending aorta susceptible to TAA. The environment includes solid mechanics, fluid mechanics, cell phenotype, and extracellular matrix composition. Advances in solid mechanics include quantification of biaxial deformation and complex failure behavior of the TAA wall. Advances in fluid mechanics include imaging and modeling of hemodynamics that may lead to TAA formation. For cell phenotype, studies demonstrate changes in cell contractility that may serve to sense mechanical changes and transduce chemical signals. Studies on matrix defects highlight the multi-factorial nature of the disease. We conclude that future work should integrate the effects of bio-chemo-mechanical factors for improved TAA treatment.

Differences in manifestations of Marfan syndrome, Ehlers-Danlos syndrome, and Loeys-Dietz syndrome

Many different heritable connective tissue disorders (HCTD) have been described over the past decades. These syndromes often affect the connective tissue of various organ systems, including heart, blood vessels, skin, joints, bone, eyes, and lungs. The discovery of these HCTD was followed by the identification of mutations in a wide range of genes encoding structural proteins, modifying enzymes, or components of the TGFβ-signaling pathway. Three typical examples of HCTD are Marfan syndrome (MFS), Ehlers-Danlos syndrome (EDS), and Loeys-Dietz syndrome (LDS). These syndromes show some degree of phenotypical overlap of cardiovascular, skeletal, and cutaneous features. MFS is typically characterized by cardiovascular, ocular, and skeletal manifestations and is caused by heterozygous mutations in FBN1, coding for the extracellular matrix (ECM) protein fibrillin-1. The most common cardiovascular phenotype involves aortic aneurysm and dissection at the sinuses of Valsalva. LDS is caused by mutations in TGBR1/2, SMAD2/3, or TGFB2/3, all coding for components of the TGFβ-signaling pathway. LDS can be distinguished from MFS by the unique presence of hypertelorism, bifid uvula or cleft palate, and widespread aortic and arterial aneurysm and tortuosity. Compared to MFS, LDS cardiovascular manifestations tend to be more severe. In contrast, no association is reported between LDS and the presence of ectopia lentis, a key distinguishing feature of MFS. Overlapping features between MFS and LDS include scoliosis, pes planus, anterior chest deformity, spontaneous pneumothorax, and dural ectasia. EDS refers to a group of clinically and genetically heterogeneous connective tissue disorders and all subtypes are characterized by variable abnormalities of skin, ligaments and joints, blood vessels, and internal organs. Typical presenting features include joint hypermobility, skin hyperextensibility, and tissue fragility. Up to one quarter of the EDS patients show aortic aneurysmal disease. The latest EDS nosology distinguishes 13 subtypes. Many phenotypic features show overlap between the different subtypes, which makes the clinical diagnosis rather difficult and highlights the importance of molecular diagnostic confirmation.

TGF-β1 affects cell-cell adhesion in the heart in an NCAM1-dependent mechanism

The contractile property of the myocardium is maintained by cell-cell junctions enabling cardiomyocytes to work as a syncytium. Alterations in cell-cell junctions are observed in heart failure, a disease characterized by the activation of Transforming Growth Factor beta 1 (TGFβ1). While TGFβ1 has been implicated in diverse biologic responses, its molecular function in controlling cell-cell adhesion in the heart has never been investigated. Cardiac-specific transgenic mice expressing active TGFβ1 were generated to model the observed increase in activity in the failing heart. Activation of TGFβ1 in the heart was sufficient to drive ventricular dysfunction. To begin to understand the function of this important molecule we undertook an extensive structural analysis of the myocardium by electron microscopy and immunostaining. This approach revealed that TGFβ1 alters intercalated disc structures and cell-cell adhesion in ventricular myocytes. Mechanistically, we found that TGFβ1 induces the expression of neural adhesion molecule 1 (NCAM1) in cardiomyocytes in a p38-dependent pathway, and that selective targeting of NCAM1 was sufficient to rescue the cell adhesion defect observed when cardiomyocytes were treated with TGFβ1. Importantly, NCAM1 was upregulated in human heart samples from ischemic and non-ischemic cardiomyopathy patients and NCAM1 protein levels correlated with the degree of TGFβ1 activity in the human cardiac ventricle. Overall, we found that TGFβ1 is deleterious to the heart by regulating the adhesion properties of cardiomyocytes in an NCAM1-dependent mechanism. Our results suggest that inhibiting NCAM1 would be cardioprotective, counteract the pathological action of TGFβ1 and reduce heart failure severity.

Role of TGFBR1 and TGFBR2 genetic variants in Marfan syndrome

OBJECTIVE

Genetic variants in transforming growth factor beta (TGF-β) receptors type 1 (TGFBR1) and type 2 (TGFBR2) genes have been associated with different hereditary connective tissue disorders sharing thoracic aortic aneurysm and dissection (TAA/D). Mutations in both TGFBR1/2 genes have been described in patients with TAA/D and Marfan syndrome (MFS), and they are associated consistently with Loeys-Dietz syndrome. The existing literature shows discordant data resulting from mutational screening of TGFBR1/2 genes in patients with MFS. The aim of the study was to investigate the role of TGFBR1/2 genetic variants in determining and/or modulating MFS clinical phenotype.

METHODS

We investigated 75 unrelated patients with MFS referred to the Center for Marfan Syndrome and Related Disorders (Careggi University Hospital, Florence) who were subjected to FBN1 and TGFBR1/2 Sanger mutational screening.

RESULTS

Forty-seven patients with MFS (63%) carried a pathogenetic FBN1 mutation. No pathogenetic mutations were detected in TGFBR1/2 genes. Ten common polymorphisms were identified in TGFBR2 and 6 in TGFBR1. Their association with cardiovascular manifestations was evaluated. Carriers of the A allele of rs11466512, delA allele of c.383delA or delT allele of c.1256-15del1T polymorphisms had a trend toward or significantly reduced z-scores (median [interquartile range (IQR)], 2.2 [1.13-4.77]; 2.1 [1.72-3.48]; 2.5 [1.85-3.86]) with respect to homozygous patients with wild-type MFS (median [IQR], 4.20 [2.39-7.25]; 3.9 [2.19-7.00]; 3.9 [2.14-6.93]). Carriers of the A allele of the rs2276767 polymorphism showed a trend toward increased z-score (median [IQR], 4.9 [2.14-7.16]) with respect to patients with wild-type MFS (median [IQR], 3.3 [1.75-5.45]). The protective effect of TGFBR1/2 genetic score including all the 4 variants was also evaluated. Patients with MFS with two or more protective alleles included in the score had statistically significant reduced aortic z-scores (median [IQR], 2.20 [1.48-3.37]) with respect to patients with 1 or no protective alleles (median [IQR], 4.20 [2.48-7.12]; P = .007). Patients with severe aortic manifestations (aortic z-score ≥ 2 or aortic surgery) showed a significantly lower prevalence of subjects with two or more protective alleles included in the genetic score (29.7%) than patients with no or milder cardiovascular involvement (63.6%; P = .029). The genetic score protective effect on global aortic manifestations severity (aortic z-score ≥ 2 or aortic surgery) was also observed at the logistic regression analysis adjusted for the presence of FBN1 gene mutations (odds ratio, 0.21; 95% CI, 0.05-0.84; P = .028).

CONCLUSIONS

In conclusion, our data reappraise the role of TGFBR1 and TGFBR2 as major genes in patients with MFS, and suggest that TGFBR1/2 genetic variants (in particular when evaluated as a burden by score) might play a role in modulating the severity of cardiovascular manifestation in MFS.

Tall stature: a difficult diagnosis?

Referral for an assessment of tall stature is less common than for short stature. Tall stature is defined as a height more than two standard deviations above the mean for age. The majority of subjects with tall stature show a familial tall stature or a constitutional advance of growth (CAG), which is a diagnosis of exclusion. After a careful physical evaluation, tall subjects may be divided into two groups: tall subjects with normal appearance and tall subjects with abnormal appearance. In the case of normal appearance, the paediatric endocrinologist will have to evaluate the growth rate. If it is normal for age and sex, the subject may be classified as having familial tall stature, CAG or obese subject, while if the growth rate is increased it is essential to evaluate pubertal status and thyroid status. Tall subjects with abnormal appearance and dysmorphisms can be classified into those with proportionate and disproportionate syndromes.

A careful physical examination and an evaluation of growth pattern are required before starting further investigations. Physicians should always search for a pathological cause of tall stature, although the majority of children are healthy and they generally do not need treatment to cease growth progression.

The most accepted and effective treatment for an excessive height prediction is inducing puberty early and leading to a complete fusion of the epiphyses and achievement of final height, using testosterone in males and oestrogens in females. Alternatively, the most common surgical procedure for reducing growth is bilateral percutaneous epiphysiodesis of the distal femur and proximal tibia and fibula.

This review aims to provide up-to-date information and suggestions about the diagnosis and management of children with tall stature.

Functional validation reveals the novel missense V419L variant in TGFBR2 associated with Loeys-Dietz syndrome (LDS) impairs canonical TGF-β signaling

TGF-β-related heritable connective tissue disorders are characterized by a similar pattern of cardiovascular defects, including aortic root dilatation, mitral valve prolapse, vascular aneurysms, and vascular dissections and exhibit incomplete penetrance and variable expressivity. Because of the phenotypic overlap of these disorders, panel-based genetic testing is frequently used to confirm the clinical findings. Unfortunately in many cases, variants of uncertain significance (VUSs) obscure the genetic diagnosis until more information becomes available. Here, we describe and characterize the functional impact of a novel VUS in the TGFBR2 kinase domain (c.1255G>T; p.Val419Leu), in a patient with the clinical diagnosis of Marfan syndrome spectrum. We assessed the structural and functional consequence of this VUS using molecular modeling, molecular dynamic simulations, and in vitro cell-based assays. A high-quality homology-based model of TGFBR2 was generated and computational mutagenesis followed by refinement and molecular dynamics simulations were used to assess structural and dynamic changes. Relative to wild type, the V419L induced conformational and dynamic changes that may affect ATP binding, increasing the likelihood of adopting an inactive state, and, we hypothesize, alter canonical signaling. Experimentally, we tested this by measuring the canonical TGF-β signaling pathway activation at two points; V419L significantly delayed SMAD2 phosphorylation by western blot and significantly decreased TGF-β-induced gene transcription by reporter assays consistent with known pathogenic variants in this gene. Thus, our results establish that the V419L variant leads to aberrant TGF-β signaling and confirm the diagnosis of Loeys-Dietz syndrome in this patient.

Association Between Migraine and Cervical Artery Dissection: The Italian Project on Stroke in Young Adults

Importance

Although sparse observational studies have suggested a link between migraine and cervical artery dissection (CEAD), any association between the 2 disorders is still unconfirmed. This lack of a definitive conclusion might have implications in understanding the pathogenesis of both conditions and the complex relationship between migraine and ischemic stroke (IS).

Objective

To investigate whether a history of migraine and its subtypes is associated with the occurrence of CEAD.

Design, Setting, and Participants

A prospective cohort study of consecutive patients aged 18 to 45 years with first-ever acute ischemic stroke enrolled in the multicenter Italian Project on Stroke in Young Adults was conducted between January 1, 2000, and June 30, 2015. In a case-control design, the study assessed whether the frequency of migraine and its subtypes (presence or absence of an aura) differs between patients whose IS was due to CEAD (CEAD IS) and those whose IS was due to a cause other than CEAD (non-CEAD IS) and compared the characteristics of patients with CEAD IS with and without migraine.

Main Outcomes and Measures

Frequency of migraine and its subtypes in patients with CEAD IS vs non-CEAD IS.

Results

Of the 2485 patients (mean [SD] age, 36.8 [7.1] years; women, 1163 [46.8%]) included in the registry, 334 (13.4%) had CEAD IS and 2151 (86.6%) had non-CEAD IS. Migraine was more common in the CEAD IS group (103 [30.8%] vs 525 [24.4%], P = .01), and the difference was mainly due to migraine without aura (80 [24.0%] vs 335 [15.6%], P < .001). Compared with migraine with aura, migraine without aura was independently associated with CEAD IS (OR, 1.74; 95% CI, 1.30-2.33). The strength of this association was higher in men (OR, 1.99; 95% CI, 1.31-3.04) and in patients 39.0 years or younger (OR, 1.82; 95% CI, 1.22-2.71). The risk factor profile was similar in migrainous and non-migrainous patients with CEAD IS (eg, hypertension, 20 [19.4%] vs 57 [24.7%], P = .29; diabetes, 1 [1.0%] vs 3 [1.3%], P > .99).

Conclusions and Relevance

In patients with IS aged 18 to 45 years, migraine, especially migraine without aura, is consistently associated with CEAD. This finding suggests common features and warrants further analyses to elucidate the underlying biologic mechanisms.

The Genetics of Aortopathies in Clinical Cardiology

Aortopathies pose a significant healthcare burden due to excess early mortality, increasing incidence, and underdiagnosis. Understanding the underlying genetic causes, early diagnosis, timely surveillance, prophylactic repair, and family screening are keys to addressing these diseases. Next-generation sequencing continues to expand our understanding of the genetic causes of heritable aortopathies, rapidly clarifying their underlying molecular pathophysiology and suggesting new potential therapeutic targets. This review will summarize the pathogenetic mechanisms and management of heritable genetic aortopathies with attention to specific forms of both syndromic and nonsyndromic disorders, including Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, and familial thoracic aortic aneurysm and dissection.

Tgfbr2 is required in osterix expressing cells for postnatal skeletal development

Transforming growth factor β (TGFβ) is known to play an important role in early skeletal development. We previously demonstrated that loss of TGFβ receptor II (Tgfbr2) in Prx1-Cre-expressing mesenchyme results in defects in long bones, joints, and the skull vault in mice resulting from reduced naïve mesenchymal proliferation and condensation that interrupted osteoblast differentiation. In contrast, others have shown that the loss of Tgfbr2 in fully differentiated mature osteoblasts results in increased bone volume. To study the role of Tgfbr2 in immature osteoblasts, we generated Osx-Cre;Tgfbr2^fl/fl mice and found defects in the postnatal development of the skull vault and long bones as compared to controls. No discernible skeletal defects were observed in newborn mice; however, at postnatal day 24 (P24), Tgfbr2-deleted mice demonstrated short stature that correlated with reduced proliferation in the growth plate. X-ray and microCT analysis of long bone and skull from P24 mice showed reduced bone volume. Histomorphometry indicated reductions in osteoblast number but not osteoclast number. Quantitative real-time PCR demonstrated mRNA levels for the osteoblast marker, Runx2, were not altered but mRNA levels of a marker for mature osteoblasts, Bglap, were down in mutant calvaria relative to controls. The mRNA of a proliferation marker, proliferative nuclear cell antigen (PCNA), was also reduced whereas the ratio of Bax2:Bcl2 was unaltered to demonstrate no change in apoptosis. These results suggest proliferation and maturation of immature osteoblasts requires Tgfbr2 signaling and that decreased bone volume in Osx-Cre;Tgfbr2^fl/fl mice is likely due to fewer mature osteoblasts.

Novel Marfan Syndrome-Associated Mutation in the FBN1 Gene Caused by Parental Mosaicism and Leading to Abnormal Limb Patterning

Marfan syndrome is an autosomal dominant disorder of the connective tissue caused by mutations in the fibrillin-1 (FBN1) gene. Mutations affecting cysteine residues within the epidermal growith factor-like calcium-binding domains (EGF_CA) of FBN1 are associated with Marfan syndrome features and, especially, with ectopia lentis. We report a novel substitution, affecting the first cysteine of an EGF_CA-binding module encoded by exon 63 of FBN1 (C2571Y), in a patient presenting with typical Marfan syndrome features but without ectopia lentis. The involvement of this particular carboxi-terminal domain in bone morphogenetic protein signaling is evidenced by patterning defects in the apendicular skeleton shown by the gain of a phalange at digit 1 and the fusion of some wrist bones. Although the mutation appeared as sporadic, detailed analysis revealed that the asymptomatic father was a gonosomal mosaic, and that aproximately 25% of his body cells carry the mutation. Based on this and previous evidence on the origin of sporadic mutations, we would like to stress the importance of detailed parental genetic screening, so the risk of recurrence may be evaluated.

Exome sequencing identified a novel SMAD2 mutation in a Chinese family with early onset aortic aneurysms

Aortic aneurysm remains a devastating disease due to its fatal complications, such as aortic dissection and rupture. A subset of aortic aneurysm is caused by genetic defect and to date more than a dozen of disease-causing genes have been discovered to account for the disease. In this study, by using whole exome sequencing, we identified a novel heterozygous missense mutation (c.833C>T, p.A278V) in the SMAD2 gene in a family with early onset aortic aneurysms. The mutation segregated in this family, was high conserved among species and predicted to be pathogenic by multiple in silico programs. To our knowledge, this is the second report that link the SMAD2 mutations to aortic aneurysm. We recommend that SMAD2 should be included in the expanding panel of genetic testing for patients with unexplained aortic aneurysms, which will facilitate genotype-phenotype correlation of SMAD2 mutations. Given the current wide application of molecular diagnosis in clinical setting, identification of the defected gene allows recognition of additional family members at risk for aortic diseases and gene-based management of the carriers.

Development of spinal deformities in the tight-skin mouse

Tight-skin (TSK) mice are commonly used as an animal model to study the pathogenesis of Marfan syndrome (MFS), but little is known of their skeletal phenotype and in particular of the development of the spinal deformities, common in MFS. Here we examined growth of the axial skeletons of TSK and wild-type(B6) mice during their period of rapid growth. The whole bodies of mice, 4–12 weeks of age, were scanned after sacrifice, by micro-computed tomography (microCT). We reconstructed three-dimensional models of the spine and ribs, and measured vertebral body heights and rib lengths using the Mac-based image-processing software “OsiriX”. Although the TSK mice were smaller than the B6 mice at 4 weeks, they experienced an early growth spurt and by 8 weeks the height, but not the width, of the vertebral body was significantly greater in the TSK mice than the B6 mice. Measurement of the angles of scoliotic and kyphotic curves post-mortem in the mice was problematic, hence we measured changes that develop in skeletal elements in these disorders. As a marker of kyphosis, we measured anterior wedging of the vertebral bodies; as a marker for scoliosis we measured asymmetries in rib length. We found, unlike in the B6 mice where the pattern was diffuse, wedging in TSK mice was directly related to spinal level and peaked steeply at the thoracolumbar junction. There was also significant asymmetry in length of the ribs in the TSK mice, but not in the B6 mice. The TSK mice thus appear to exhibit spinal deformities seen in MFS and could be a useful model for gaining understanding of the mechanisms of development of scoliosis and kyphosis in this disorder.

Molecular modeling and molecular dynamic simulation of the effects of variants in the TGFBR2 kinase domain as a paradigm for interpretation of variants obtained by next generation sequencing

Variants in the TGFBR2 kinase domain cause several human diseases and can increase propensity for cancer. The widespread application of next generation sequencing within the setting of Individualized Medicine (IM) is increasing the rate at which TGFBR2 kinase domain variants are being identified. However, their clinical relevance is often uncertain. Consequently, we sought to evaluate the use of molecular modeling and molecular dynamics (MD) simulations for assessing the potential impact of variants within this domain. We documented the structural differences revealed by these models across 57 variants using independent MD simulations for each. Our simulations revealed various mechanisms by which variants may lead to functional alteration; some are revealed energetically, while others structurally or dynamically. We found that the ATP binding site and activation loop dynamics may be affected by variants at positions throughout the structure. This prediction cannot be made from the linear sequence alone. We present our structure-based analyses alongside those obtained using several commonly used genomics-based predictive algorithms. We believe the further mechanistic information revealed by molecular modeling will be useful in guiding the examination of clinically observed variants throughout the exome, as well as those likely to be discovered in the near future by clinical tests leveraging next-generation sequencing through IM efforts.

Aetiology and management of hereditary aortopathy

Aortic aneurysms are a major health problem because they account for 1-2% of all deaths in the Western population. Although abdominal aortic aneurysms (AAAs) are more prevalent than thoracic aortic aneurysms (TAAs), TAAs have been more exhaustively studied over the past 2 decades because they have a higher heritability and affect younger individuals. Gene identification in both syndromic and nonsyndromic TAA is proceeding at a rapid pace and has already pinpointed >20 genes associated with familial TAA risk. Whereas these genes explain <30% of all cases of familial TAA, their functional characterization has substantially improved our knowledge of the underlying pathological mechanisms. As such, perturbed extracellular matrix homeostasis, transforming growth factor-β signalling, and vascular smooth muscle cell contractility have been proposed as important processes in TAA pathogenesis. These new insights enable novel treatment options that are currently being investigated in large clinical trials. Moreover, together with the advent of next-generation sequencing approaches, these genetic findings are promoting a shift in the management of patients with TAA by enabling gene-tailored interventions. In this Review, we comprehensively describe the molecular landscape of familial TAA, and we discuss whether familial TAA, from a biological point of view, can serve as a paradigm for the genetically more complex forms of the condition, such as sporadic TAA or AAA.

An ENU-induced p.C225S missense mutation in the mouse Tgfb1 gene does not cause Camurati-Engelmann disease-like skeletal phenotypes

Camurati-Engelmann disease (CED) is a rare sclerosing bone disorder in humans with autosomal dominant inheritance. Mutations in the gene (TGFB1) that encodes transforming growth factor-β1 (TGF-β1) are causative for CED. TGF-β1 signaling is enhanced by the CED-causing mutations. In this study, we performed Tgfb1 mutation screening in an ENU-mutagenized mouse genomic DNA library. We identified a missense mutation in which cysteine was substituted by serine at position 225 (p.C225S), that corresponded to the CED-causing mutation (p.C225R). TGF-β1 mutant protein carrying p.C225S was secreted normally into the extracellular space. Reporter gene assays showed that the p.C225S mutants enhanced TGF-β signaling at the same level as p.C225R mutants. We generated p.C225S homozygous mice and confirmed that the mature TGF-β1 levels in the culture supernatants of the calvarial cells from the homozygotes were significantly higher than those from wild-type mice. Although the skull and femur are sclerotic in CED, these phenotypes were not observed in p.C225S homozygous mice. These results suggest that human and mouse bone tissue react differently to TGF-β1. These findings are useful to pharmacological studies using mouse models in developing drugs that will target TGF-β signaling.

Loss-of-function mutations in the X-linked biglycan gene cause a severe syndromic form of thoracic aortic aneurysms and dissections

PURPOSE

Thoracic aortic aneurysm and dissection (TAAD) is typically inherited in an autosomal dominant manner, but rare X-linked families have been described. So far, the only known X-linked gene is FLNA, which is associated with the periventricular nodular heterotopia type of Ehlers-Danlos syndrome. However, mutations in this gene explain only a small number of X-linked TAAD families.

METHODS

We performed targeted resequencing of 368 candidate genes in a cohort of 11 molecularly unexplained Marfan probands. Subsequently, Sanger sequencing of BGN in 360 male and 155 female molecularly unexplained TAAD probands was performed.

RESULTS

We found five individuals with loss-of-function mutations in BGN encoding the small leucine-rich proteoglycan biglycan. The clinical phenotype is characterized by early-onset aortic aneurysm and dissection. Other recurrent findings include hypertelorism, pectus deformity, joint hypermobility, contractures, and mild skeletal dysplasia. Fluorescent staining revealed an increase in TGF-β signaling, evidenced by an increase in nuclear pSMAD2 in the aortic wall. Our results are in line with those of prior reports demonstrating that Bgn-deficient male BALB/cA mice die from aortic rupture.

CONCLUSION

In conclusion, BGN gene defects in humans cause an X-linked syndromic form of severe TAAD that is associated with preservation of elastic fibers and increased TGF-β signaling.Genet Med 19 4, 386-395.

Marfan syndrome: Report of a complex phenotype due to a 15q21.1 contiguos gene deletion encompassing FBN1, and literature review

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder that primarily involves skeletal, ocular, and cardiovascular systems with large inter- and intra-familial variability in terms of age of onset, severity, and aortic disease. The causal gene, FBN1, encodes for fibrillin 1, a multi-domain glycoprotein essential for many biological functions, including deposition and formation of elastic fibers. Reports describing chromosomal alterations involving FBN1 are rare, but in the last years their number has increased after copy number state analyses, such as multiplex ligation-dependent probe amplification and microarray-based comparative genomic hybridization, were adopted as routine diagnostic tools. Herein we report a patient with MFS and an atypical facial appearance and neuropsychiatric involvement likely not attributable to MFS due to a 15q21.1 deletion that involves part of FBN1 and 13 additional contiguous genes listed in OMIM. We compare his phenotype with those of the few patients described in the literature who share similar 15q11.2 deletions. This report expands the phenotype of patients with 15q11.2 deletion involving FBN1 and its contiguous genes, and suggests a possible role for these other genes in the pathogenesis of the observed unusual clinical signs that are not explained by FBN1 haploinsufficiency. © 2016 Wiley Periodicals, Inc.

Network biology concepts in complex disease comorbidities

The co-occurrence of diseases can inform the underlying network biology of shared and multifunctional genes and pathways. In addition, comorbidities help to elucidate the effects of external exposures, such as diet, lifestyle and patient care. With worldwide health transaction data now often being collected electronically, disease co-occurrences are starting to be quantitatively characterized. Linking network dynamics to the real-life, non-ideal patient in whom diseases co-occur and interact provides a valuable basis for generating hypotheses on molecular disease mechanisms, and provides knowledge that can facilitate drug repurposing and the development of targeted therapeutic strategies.

A Case Based Approach to Clinical Genetics of Thoracic Aortic Aneurysm/Dissection

Thoracic aortic aneurysm/dissection (TAAD) is a potential lethal condition with a rising incidence. This condition may occur sporadically; nevertheless, it displays familial clustering in >20% of the cases. Family history confers a six- to twentyfold increased risk of TAAD and has to be considered in the identification and evaluation of patients needing an adequate clinical follow-up. Familial TAAD recognizes a number of potential etiologies with a significant genetic heterogeneity, in either syndromic or nonsyndromic forms of the manifestation. The clinical impact and the management of patients with TAAD differ according to the syndromic and nonsyndromic forms of the manifestation. The clinical management of TAAD patients varies, depending on the different forms. Starting from the description of patient history, in this paper, we summarized the state of the art concerning assessment of clinical/genetic profile and therapeutic management of TAAD patients.